1. Field of the Invention
The invention relates to video signal processing apparatus and method for processing a video signal which is displayed in a video output apparatus such as television (TV) monitor, liquid crystal display panel, or the like.
2. Related Background Art
FIG. 9 is a block diagram showing a construction of a conventional video signal processing apparatus. In the diagram, reference numeral 101 denotes a CCD sensor for converting a received video image into an electric signal; and 102 indicates a photo taking system signal processing circuit. The photo taking system signal processing circuit 102 forms a luminance signal by performing a color carrier removal, an aperture compensation, a gamma process, and the like to the video signal that is outputted from the CCD sensor 101 and, at the same time, forms color difference signals by performing a color interpolation, a matrix conversion, a gamma process, a gain adjustment, and the like to the video signal, and generates a video signal of YUV or the like.
Reference numeral 103 denotes a TV system signal processing circuit for generating a TV signal by performing processes such as chroma encoding process, band compensation, composite signal formation, and the like to the YUV signal that is generated from the photo taking system signal processing circuit 102. Reference numeral 104 denotes an LCD controller for generating a drive pulse necessary for an LCD display and converting the TV signal that is generated from the TV system signal processing circuit 103 into an RGB signal to be displayed on an LCD panel 105. Reference numeral 105 denotes the LCD panel for displaying the RGB signal that is outputted from the LCD controller 104 by an LCD device as a visible image.
Reference numeral 106 denotes a TV monitor for displaying a video image in accordance with each TV system such as NTSC system, PAL system, or the like. In the NTSC system and the PAL system, the numbers of pixels of the CCD sensors which are necessary differ. For example, in the NTSC system, the number of pixels is equal to 752 (in the horizontal direction)xc3x97485 (in the vertical direction). In the PAL system, the number of pixels is equal to 736 (horizontal)xc3x97575 (vertical). The number of pixels of the LCD panel which is used in a photo taking apparatus such as cam coder, digital camera, or the like characterized by portability is, hitherto, so small to be 279 (horizontal)xc3x97220 (vertical).
Although an LCD panel having the large number of pixels has been developed in recent years, the number of pixels is equal to up to 550 (horizontal)xc3x97220 (vertical) and is equal to xc2xd of that of the CCD sensor of the NTSC system. Hitherto, in case of providing an apparatus which can cope with both of the NTSC system and the PAL system using the CCD sensor (752 (horizontal)xc3x97485 (vertical)) for the NTSC system, in case of using the PAL system, 575 lines in the vertical direction are formed by compensating the insufficient lines from 485 lines in the vertical direction.
In case of displaying on an LCD panel of the small number of pixels comprising 550 (horizontal)xc3x97220 (vertical) pixels or the like, although the lines of the number of almost one field can be displayed in the NTSC system, the image data of 1/7 line of the field cannot be displayed in the PAL system. In case of displaying the video signal of the PAL system onto the LCD panel, seven lines are thinned out by one line and the reduced video image is displayed. Such a thinning process of the lines is performed by an LCD controller designed so as to drive the LCD panel.
On the other hand, in case of outputting the video signal of the PAL system by using the CCD sensor having the number of lines according to the NTSC system, the insufficient lines are compensated by an interpolation or the like. However, when the LCD controller displays the supplied video signal of the PAL system to the LCD panel as mentioned above, the video signal is thinned out and displayed.
In case of displaying the video signal onto the LCD panel by the PAL system, consequently, a phenomenon such that the original video signal is thinned out or the like occurs and a quality of the image displayed on the LCD panel is remarkably deteriorated.
Particularly, in case of super-imposing character information or the like for a user interface onto a video image and displaying the super-imposed video image, since the character information is thinned out at the time of the LCD display of the PAL system, fine lateral lines of the characters are deleted and the function to correctly display information is deteriorated. FIGS. 10A to 10D are diagrams showing an example of a display in which a part of the character has been deleted.
Although the characters of xe2x80x9cERASExe2x80x9d are displayed in the TV monitor 106 (FIG. 10A), the character of xe2x80x9cExe2x80x9d that should inherently be shown in FIG. 10B is thinned out and is not correctly displayed on the LCD panel 105. As mentioned above, the character of xe2x80x9cExe2x80x9d is seen like xe2x80x9cCxe2x80x9d as shown in FIG. 10C or is seen like xe2x80x9cFxe2x80x9d as shown in FIG. 10D, so that the character information cannot be correctly displayed.
The above problem occurs because of the use of the liquid crystal display for converting the output of the CCD sensor having the number of lines for the NTSC system into the TV signal for the PAL system and displaying an image.
Hitherto, a digital camera apparatus which can easily switch an external video output according to the NTSC system and an external video output according to the PAL system is not known yet.
It is an object of the invention to provide image processing apparatus and method which can solve each of or all of the foregoing problems.
Under such an object, another object of the invention is to reduce the deterioration of a quality of an image that is displayed on a display.
Still another object of the invention is to reduce the deterioration of a quality of an image that is displayed when the image is displayed by using a general liquid crystal display.
Further another object of the invention is to provide video signal processing apparatus and method which can perform a liquid crystal display without a deterioration of a picture quality even by using a CCD sensor of the NTSC system when an output of the PAL system is generated.
To accomplish the above objects, according to a first aspect of a preferred embodiment of the invention, there is provided a video signal processing apparatus comprising; storage means for storing video data; read-out means for reading out the stored video data; interpolating means for interpolating the read-out video data; display means for displaying the interpolated video data; and interpolation control means for matching the data in the portion that is interpolated by the interpolating means to the data in a portion that is not displayed by the display means when the video data is displayed.
Further another object of the invention is not to deteriorate a display quality of data which is super-imposed and displayed together with an image.
Under the above object, in the video signal processing apparatus according to the first aspect of the invention, the storage means stores the video data comprising photographed image data and video data for super-impose; the read-out means individually reads out the stored photographed image data and video data for super-impose; the interpolating means interpolates the photographed image data and the video data for super-impose which are individually read out; the display means displays the interpolated photographed image data and video data for super-impose onto a same picture plane; and the interpolation control means matches the photographed image data and video data for super-impose in the portions which are interpolated by the interpolating means to the data in the portion that is not displayed by the display means, respectively.
Further another object of the invention is to reduce a deterioration of a picture quality when an output of an image pickup device having the pixels of the number larger than the number of pixels that is required by a standard television system is displayed as an image by using a display having the display pixels of the number smaller than the number of pixels that is required by the standard TV system.
Further another object of the invention is to provide a digital camera apparatus which can easily cope with various standard television systems.
Further another object of the invention is to reduce a deterioration of a quality of an image that is displayed on a display of a digital camera.
The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings.